PSI - Issue 57

Haelie Egbert et al. / Procedia Structural Integrity 57 (2024) 179–190 Haelie Egbert et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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2. Fatigue Test Methodology The standard SAE J1619 [11] STB test gear and fixture were used to perform gear tooth bending fatigue tests, as shown in Figure 1. Test gear geometrical parameters are given in Table 1. A slight modification of the supporting fixture to the gear was made to improve the contact conditions on the reaction tooth [12]. The fixture facilitates contact of two teeth spaced 4 teeth apart. The upper tooth, referred to as the test tooth, contacts the upper anvil, which is aligned through a common shaft and is free to rotate. Load is applied to the upper anvil through a ball bearing on which the loading piston contacts. The purpose of this ball bearing is to negate the effects of small amounts of misalignment between the hydraulic piston and desired load axis of the fixture. The lower tooth is contacted closer to the root to reduce applied bending stresses and is referred to as the reaction tooth. As the stresses are lower in the reaction tooth it is not intended to fail. Reaction teeth are only used once. Force control was achieved through a load cell (Interface P/N 1020FPJ-25K-1B) installed in-line with the hydraulic piston. A Keyence IL-065 displacement laser monitored deflection of the SAE fixture head.

Table 1. SAE J1619 Single Tooth Bending Gear Design Number of Teeth 34 Module 4.23mm Pressure Angle 20deg Pitch Diameter 143.934mm Root Diameter 131.775mm Base Diameter 135.252

Figure 1. SAE J1619 Single Tooth Bending Fixture